Heat sealing mechanism for wrapping machines



J. S. BARTLO ETAI.

HEAT SEALING MECHANISM FOR WRAPPING MACHINES Nov. 21, 1967 6 Sheets-Sheet l Filed .April 16, 1964 7 m www S.

NOV 21, 1957 .1.5. BAR-n.0 ETAL 3,353,332 y HEAT SEALING MECHANISM FOR WRAPPING MACHINES Filed April 16, 1964 6 Sheets-Sheet 2 lu' i- INVENTORS uaH/Y i ARTLo R/CHAKD H. PROVST BY 267m 4 )Leu 1 NOV- 21, 1967 .1. s. BARTLO ETAL 3,353,332

HEAT SEALING MECHANISM FOR WRAPPING MACHINES Filed April 1e, 1964 e sheets-Sheng INVENTORS R/(HARD P20 V057- BY dwz c# /fz mmh? S' J. s'. BARTLO ETAL 3,353,332

HEAT SEALING MECHANISM FR WRAPPING MACHINES Filed April 16,]1964 Nov. 21, 1967 6 Sheets-Sheet 4 NWN evi O I I l l I I l I l l I lll. iwwwio- I N VEN TOR5 4 dof/N 5. BA'QT/ o R/cHA/zp H. mea vas 7 mwN J. s. BARTLO rsTAl.` 3,353,332

Nov. 21, 1967 HEAT SEALING MECHANISM FOR WRAPPING MACHINES 6 Sheets-Sheet 5 Filed April 16, 1964 73 INVENTORs Sol (JOHN 5. @ARTLO @lc/MRD H PVS'T Nov. 21, 1967 .1. s. BARTLO ETAL 3,353,332

HEAT SEALING MECHANISM FOR WRAPPING MACHINES Filed April 16, 1964 6 Sheets-Sheet 6 `El E-' l l ElldO/-N S. BARTLO R/CHARZ H. PROVOST :EJ- Cibi BY Emi?? I N VEN TORS United States Patent Office 3,353,332 Patented Nov. 21, 1967 3,353,332 HEAT lSEALING MECHANISM FOR WRAPPING MACHINES John S. Bartlo, Longmeadow, and Richard H. Provost,

Shrewsbury, Mass., assignors to Package Machinery Company, East Longmeadow, Mass., a corporation of Massachusetts Filed Apr. 16, 1964, Ser. No. 360,395 17 Claims. (Cl. 53-379) The present invention relates to improvements in wrapping machines and more particularly to improved mechanism for heat sealing folded wrapper portions.

The object of the invention is to provide a simple and relatively inexpensive mechanism for sealing wrapped articles which are intermittently advanced through a wrapping machine.

Another object of the invention is to provide means for attaining the above end which may readily be incorporated in existing machine designs, and/ or added to existing machines already in operation.

A further object of the invention is to provide means for obtaining the above ends which have a great versatility in handling a wide variety of wrapped articles and which require a minimum of space requirements.

These objects are obtained in a wrapping machine of the type usually employing an elevator and having a reciprocating conveyor for advancing articles through a wrapper folding channel. In accordance with the invention a `sealing channel is aligned with the folding channel so that successive wrapped articles may be advanced by the reciprocating conveyor to a given position within said sealing channel. Means are then provided for forcibly engaging each article with means for heat sealing lapped portions of the wrapper while an article is at rest in the designated position.

It is advantageous to provide -a second conveyor for discharging articles from the sealing chamber during the forward stroke of the first mentioned conveyor so as to avoid creating a line of articles which could build up undesirable pressures on each other. In heat sealing many wrapper materials, particularly olelins, it is preferable to employ a heating element with an endless belt interposed between it and the folded wrapper portions so as to prevent any tendency of the wrapper material to adhere to the heated element. Further, in order to allow the heat sealed wrapper portions to set, the sealing channel should be of such a length that the articles may remain in contact with the endless belts and with no relative motion therebetween after they have been advanced beyond the heated elements. It is, therefore, preferable that the rate of advance of the second conveyor be substantially the same as the rate of advance of the first conveyor, so that with two articles in the sealing channel, there will be no tendency of the belts to move relative to either.

The second conveyor is advantageously driven from the reciprocating conveyor which is `of the type comprising a plurality of paddles, 4at least one of which is swingable over an article being advanced on its return stroke. Thus the return stroke of such a conveyor must be suflicient to dispose the swingable paddle a substantial distance behind the article over which it has been swung. Where the drive for the sealing channel conveyor is derived from such a reciprocating conveyor, it is preferable to delay actuation of the second conveyor until approximately the time of contact of the swingable paddle with the article next to be advanced into the sealing cham-ber. The end result is that the spacing between articles in the sealing channel is substantially less than the spacing between articles in the folding channel, which therefore minimizes the necessary length of the sealing chamber.

The above and other related objects and features of the invention will be apparent from a reading of the following description of the disclosure found in the accompanying drawings and the novelty thereof pointed ont in the appended claims.

In the drawings:

FIG. l is an elevation showing in essentially diagrammatic form a wrapping machine embodying the present invention;

FIG. 2 is a enlarged view of a clutch unit seen in FIG. l and taken on section line II-II in FIG. 4;

FIG. 3 is a section taken on line III-III in FIG. 4;

FIG. 4 is a section taken on line lV-IV in FIG. 2;

FIG. 5 is a fragmentary view looking in the direction of arrow A in FIG. 4;

FIG. 6 is an enlarged view of a portion of the heat sealing channel seen in FIG. l;

FIG. 7 is a section taken on line VII--VII in FIG. 6;

FIG. 8 is a schematic showing of an electric circuit employed herein;

FIG. 9 is a section taken on line IX-IX in FIG. 6;

FIG. l0 is a section similar to that of FIG. 7 showing a modified embodiment of the invention;

FIGS. 11 and l2 are perspective views of two different types of wrapper folds that are sealed by the machine of the present invention.

The present invention finds utility in Vthat type of wrapping machine wherein articles are intermittently advanced through and discharged from a Wrapper folding channel. A machine of this type is shown in U.S. Patent No. 2,704,592 and the present disclosure, for illustrative purposes, represents a modification of that machine, The wrapping machine referred to comprises an infeed conveyor 10 which advances successive articles onto a pivotally mounted eievator 12 when the latter is in its lower position. The leading end of a web W is draped over a roll 14 and is partially encircled about the article as it is advanced onto the elevator and further encircled therein as the elevator is raised to an upper position aligned with a folding channel 16.

Vith the elevator 12 in its upper position, a reciprocating conveyor 18 is actuated to advance the article (referred to as al) into the folding channel to a position indicated by the article a2. The elevator comprises a pair of paddles 20 and 22. With the paddle 20 being effective to advance articles from the position a1 to a2.

In connection with the conventional components of the wrapping machine, it will be noted that at some point after the elevator l2 is raised to its upper position a knife 24 is actuated to sever the web W at a point where the severed end will lap the leading end of the web beneath the article as it is advanced to the a2 position. These transversely lapped portions of the Wrapper may be heat sealed by a unit indicated at 26. The wrapper extensions extending beyond the end faces of the article may be folded in several different ways using known means. For present purposes the essential variations to be considered are the use of Wrapper folding instrumentalities which fold the wrapper extensions in lapped relation against the end faces of the article as illustrated in FIG. l1 or the use of wrapper folding instrumentalities which fold such extensions against the end face and then lap these folded extensions against the bottom face of the article as indicated in FIG. l2.

A sealing channel 28 is aligned with the folding channel 16. The forward paddle 22 of the conveyor 18 advances successive articles from the position of article a2 to a given position (indicated by the article a3) in the sealing channel 28. The use of the paddle 22 to advance articles from the folding channel and in so doing to complete the wrapper folding process, is part of the teaching of the above-mentioned patent. It will be apparent that on the return stroke of the elevator, articles a2 and a3 will remain in the positions to which they have been advanced, inasmuch as the paddle 22 is pivotally mounted on a carriage 30 which is a component of the conveyor 18. Thus, on each reciprocation of the conveyor 18 paddle 20 advances articles from the position of a1 to a2 and the paddle 22 advances articles from the position of a2 to a3. The detailed construction for such operation and the other conventional components of the wrapping machine are well known to those in the art and reference may be made to the above-mentioned patent for further details, if deemed necessary.

Upon advance of an article to the position a3 means are actuated for forcibly engaging the article with heated sealing elements which heat seal lapped portions of the wrapper. Where the wrapper extensions are lapped against the end faces of the article, side sealing elements 32 are forcibly engaged with the end faces of the article to obtain the desired sealing of the wrapper. Where the wrapper extensions are lapped against the undersurface of the article (as in FIG. 12) pressure units 34 are engaged with the upper surface of the article to force the article into clamped relation against bottom sealing units 36 which are generally aligned with the oor of the folding channel 16 at opposite sides thereof.

After actuation of the heat sealing means, the articles are then advanced through the heat sealing chamber 28 preferably by the use of a conveyor comprising a pair of chains 38 having spaced lugs 40 thereon. Advantageously, means next to be described are provided for advancing the chains 38 during the forward stroke of the conveyor, 18 so that successive pairs of lugs 40 will advance the article from the position a3 to the position a4, as other lugs advance preceding articles to the positions a5, as and a7. The articles upon reaching the position a6 are discharged onto a roller conveyor 42 from which they may be removed by the machine attendant or otherwise taken from the machine.

Preferably the drive for the chains 38 is derived directly yfrom movement of the reciprocating conveyor 18. The chains 38 are trained around sprockets 44 which are drivingly connected to a rotatable tube on shaft 46 at the infeed end of the sealing channel 28. A sprocket 48 is also secured to the rotatable tube on shaft 46 and connected by chain t) to a sprocket 52 which is drivingly connected to a gear 54. The gear 54 meshes with a gear 56 which is drivingly connected to a sprocket 58. The sprocket 58 is connected to a sprocket 6) through chain 62.

This input drive for the sealing channel conveyor includes a clutch mechanism 64. The sprocket 69 may be considered as the drive output of this clutch mechanism and a pinion 66 is the drive input for the clutch. The pinion 66 meshes Iwith a rack 68 secured to the conveyor carriage 30. The clutch 64 functions to rotate the sprocket 60 and advance the conveyor chain 38 during the latter portion of the advance stroke of the conveyor 18 and then disconnects the conveyor drive during the return stroke of the conveyor 18, all of which will be more lfully apparent from the following detailed description of the clutch mechanism 64.

Having reference to FIGS. 2, 3 and 4, .it will be seen that the pinion 66 is rotatably mounted on a shaft 70 projecting from a fixed plate 72. A pawl carrier 74 is secured to the pinion 66 by screws 76. A pawl 78 is pivotally mounted' on the carrier 74 by a shoulder screw 80. A ratchet wheel 82 is secured to the sprocket 60 by screws 84 with both the wheel 82 and pinion 66 being freely rotatable relative to the shaft 70. At this point it will be also noted that the pinion 66, pawl carrier 74, ratchet wheel 82 and sprocket 60 are held in assembled relation on the shaft 74) between appropriate thrust bearings by a collar 86.

The ratchet wheel 82 has a single tooth 88 which is arranged to be engaged by a tooth 90 secured to the end of the pawl 78. A spring 92 compressed between the opposite end of the pawl '78 and a pivot block 94 secured to the pawl carrier 74 urges the tooth 98 into engagement with the ratchet wheel 82 and then into driving engagement with the tooth 88 upon a predetermined rotation of the pawl 78 relative to the ratchet wheel 82. The clutch mechanism is also of the single revolution type having a fixed starting point for each cycle of operation. A tooth 96 is secured to an arm 98 which is pivotally mounted on a stud 100 projecting from the fixed plate 72. A spring 102 urges the tooth 96 into engagement with the tooth 88 to maintain the ratchet wheel 82 in this given position during reverse rotation of the pinion 66.

Operation of the clutch 64 will be described at the commencement of the forward stroke of the conveyor 18. At this point it will be noted that the paddle 22 is spaced a substantial distance from the rear face of the article a2. Initial rotation of the pinion 66 in a counterclockwise direction as the carriage 30 moves through its forward stroke does not impart any motion to the output sprocket 60 as the tooth 9) rides freely over the surface of the ratchet wheel 82. After the pinion 66 has rotated a predetermined distance, illustrated at 240, the tooth 90 engages the tooth 88 at which point the paddle 22 will have engaged the rear face of the article a2. As the forward stroke of the conveyor 18 is completed, the conveyor chains 38 will be advanced as the sprocket 60 is now being driven through the clutch. Thus, are article a2 moves into the position of the article a3 as the latter is being advanced toward the position of article a4- The rate of advance of the articles in the folding channel and in the sealing channel being the same. Upon cornpletion of the forward stroke of the conveyor 18, article a2 will be fully advanced to the given position, at a3, in the sealing channel 28 by conveyor paddle 22. At this point the ratchet wheel 82 will have completed one full revolution and will be held stationary by tooth 96 as the pinion 66 and pawl 78 rotate in a clockwise direction during the return stroke of the conveyor carrier 30.

It will be noted that the delayed action of the clutch mechanism 64 results in the articles within the sealing channel 28 being spaced apart a distance substantially less than the spacing between the articles in the wrapping machine as evidenced by the spacing of articles a1 and a2. The full advantages of this relationship will be referred to at a later point.

Occasionally a jam will occur in the folding channel 16 which necessitates retracting the conveyor 18 before it has completed a full forward stroke. In the event such operation of the conveyor 18 is required after advance of the chains 38 has started, means are provided for automatically reversing the movement of these chains in order to maintain the lugs 40 in proper register with the next successive package which would be fed to the sealing channel.

For these purposes, a pin 104 is slidably mounted in the ratchet Wheel 82 and engageable with a recess 106 in the pawl carrier 74 to provide a secondary driving connection between the pinion 66 and sprocket 60. The pin 104 has a square shank 108 which is held against rotation by a slot 109 in the sprocket 60. A cam follower 110 is rotatably mounted on the outer end of the pin 104 as is an angularly Ibent strap 112. A compression spring 114 is carried by a recess in the sprocket 60 and bears against the strap 112 to urge the pin 104 out of engagement with the recess 186 and cause the cam follower 110 to engage the radial face of a cam 116.

The cam 116 is secured on the outer end of the shaft 70 by the illustrated clamping nuts 118, 120 which enable accurate adjustment of the cam 116 axially of the shaft 70, with means being provided for preventing relative rotation between the cam 116 and the shaft 70. A depression 122 in the cam face is thus maintained in a given angular position relative to the recess 106 in the pawl carrier 74.

In normal operation the ratchet wheel 82 (FIG. 2) at the start of each cycle is in the illustrated position wherein the roller 110 (FIGS. 4 and 5) is held into the depression 122 of the cam 116. The recess 106 in this start position is angularly spaced from the pin 104 approximately 240, this being the same spacing as the pawl tooth 90 from the ratchet tooth S8. When the pinion 66 has rotated in a counterclockwise direction this distance of 240, the recess 106 is aligned with the pin 104. Therefore, as the sprocket 60 commences its rotation, the pin 104 will rotate relative to the shaft 70. As this occurs, the follower 110 is displaced causing the pin 104 to enter the recess 106. Upon completion of the forward stroke of the conveyor 18, the ratchet wheel 82, as brought out above, has completed one full revolution at which time the follower 110 again enters the `depression 122 of the cam 116 and the pin 104 is withdrawn from the recess 106, thus permitting reverse rotation of the pinion 66 as the sprocket 60 remains stationary during the return stroke of the conveyor 18.

However, in the event that the conveyor 18 did not complete its full forward stroke before being moved in a reverse direction, the pin 104 would, at that time, be engaged with the recess 106 so that as the pinion 66 rotates in reverse direction the sprocket 60 would likewise rotate in a reverse direction until the follower 110 entered the cam depression 122 to withdraw pin 104 from the recess 106. Thus the conveyor lugs 40 would be returned into proper register with the advance of subsequent articles into the sealing channel. It will also be apparent that should the conveyor 18 be operated in a reverse direction before pawl tooth 90 engages ratchet tooth 88, sprocket 60 will si-rnply remain stationary.

To complete the description of the conveyor for the sealing channel 28, it will be pointed out that the sprocket 48 is secured to a rotatable tube on shaft 46 and that the sprockets 44 are keyed thereto to permit adjustment of the chains 38 towards and away from each other for different package sizes. Each of the chains 38 moves along a closed path defined by sprockets 124, 126 (these sprockets being adjustable to properly tension the chain) 128 and 130. The upper runs of the chains are also supported by support members 132, 134, 136 with a lower support member 138 also being provided to further define the path of travel of each chain. Means are provided for shifting each set of sprockets 44, 124, 126, 128, 130 and the supports 132, 134, 136 and 138 simultaneously towards and away from each other to adjust the spacing between the chains 38.

Referring now to FIGS. 6, 7 and 8, the constructional details of the sealing channel will be described. in these iigures the sealing channel is symmetrical on opposite sides of the sealing channel and reference will be made to elements on one side or the other without distinction. The chain support 132 is secured by screws 140 to the bottom sealing element 36. The bottom sealing element 36 is in turn secured to an upright plate 142 by screws 144 and spaced therefrom by an insulating plate 146. The plate 142 is secured by screws 143 to a base plate 150, which is secured to a cast bracket 152 -by screws 153 with both of the brackets 152 being slidably mounted on a pair of transverse rods 154 and connected by nuts 156 to an adjusting screw S having threads of opposite hand at its two ends to enable simultaneous movement of the brackets 152 and the elements mounted thereon towards and away from each other. The screw 158 is rotated by the means previously referred to for adjusting the chains 38 towards and away from each other to accommodate various size packages.

The side sealing elements 32 each comprise a heated plate 160 having a removable sealing die 162 secured thereon. The face of the sealing die indicated at f (FIG. 6) which is to seal the end faces of the article, is spaced inwardly from the corner edges of the articles so that no sealing heat and pressure is applied to these edges.

The plate (FIGS. 6, 7 and 9) has a pair of upwardly projecting straps 164 secured to its rear surface. Nuts 166 clamp each strap 164 on a rod end 168 which pivotally receives a stud 170 projecting from a bar 172. The bars 172 are secured -by screws 174 to the upper end of a vertical plate 176. The plate 176 is supported by the base plate 150 with gusset plates 178 being secured to the two plates by screws 180 to assure rigidity of the unit. A rod end 182 projects centrally from the lower surface of the heated plate 160 and is pivotally connected to the piston rod 184 of a double acting air motor 186. The opposite end of the air motor 136 is pivotally connected by a pin 188 to lugs 190 on the base plate 150. It will also be apparent that an appropriate clearance opening is provided in the plate 176 for the motor 186. In FIG. 7 the piston rod 134 is projected to bring the die 162 into its operative position as will later be eX- plained.

It is preferable that belts be interposed between the heat sealing elements (36 and 162) and the articles being sealed. These belts are preferably formed of fiberglass and impregnated with polytetrailuoroethylene to prevent any tendency of the wrapper material to adhere to the heated elements and to thereby insure more eective heat sealing of the lapped wrapper portions.

Thus it will be noted that an endless belt 190 extends over the upper surfaces of each bottom sealing unit 36. More specifically, the path of travel of each belt 190 is dened -by the upper surface of the element 36, an unheated support plate 192 (FIG. 6), a flanged roll 193 (FIG. l) and a shaft 195. The belt then extends back to the forward end of the -bottom sealing element 36. The belt 190 is laterally guided around the forward end of the sealing element 36 by a block 191 (FIG. 9), at its inner side and by an extension of the insulating plate 146 at its outer side. Each block 191 is slotted to receive the sprockets 44 and 130 and is secured to the element to slide these sprockets on their respective shafts when adjusting the width of the heat sealing channel.

Endless belts 194 are trained over the opposed faces of the side sealing elements 32, being trained around pulleys 196 which are rotatably mounted on shafts 198 and 200 (FIGS. 1, 6 and 9). The shaft 198 is secured to a bracket 202, which in turn is secured to the plate 142 by screws 204. A dead plate 206 is secured to the bracket 202 by screws 208 to facilitate advance of articles from the wrapping channel to the sealing channel. The pulley shaft 200 is mounted -by appropriate brackets connected to the opposite end of the plate 142. lt will be noted from FIG. 7 that the side sealing element is thus disposed between the runs of the belt 194 whiie being free to be moved from an engaging position to a position spaced from the inner surface of said belt.

The pressure units 34 each comprise a pair of pressure plates 210 (FIGS. 6 and 7) which are yieldingly mounted on a bar 212. More specifically, screws 214 are vertically adjusted relative to the bar 212 -by nuts 216. A shoulder screw 217 is threaded into the lower end of each screw 214 and connes a spring 218 between the pressure plate 210 and a washer 219. The pressure plates 210 are therefore able to yield relative to the shoulder screws 217 against the action of the springs 218. The bar 212 has a pair of upwardly projecting rods 220 which are slidingly received in a plate 221 which in turn is secured to a bracket 222. The brackets 222 are mounted on a common adjusting screw 223 which has threads of opposite hand Vat its two ends and is rotated by the same means that adjusts the conveyor chains 38 towards and away from each other so as to properly position the pressure plates 34 for different size packages. A double-acting air cylinder 224 is secured to the plate 221 with its piston rod 226 secured to the bar 212. Upon actuation of the motor 224 the pressure plates 210 will engage the article positioned therebeneath to force it against the bottom sealing element 36 to thereby heat seal wrapper extensions lapped beneath the article as indicated in FIG. l2. The stroke of the piston rod 226 is, of course, limited so that the shoulder screws 217 will not strike the article in any manner which would cause an objectionable marking. The provision of the double pressure plates 213 in each f the units 34 is preferable in order to get a substantially even pressure distribution throughout the full range of article widths for which the machine is intended to handle. The illustrated article would be the widest article in the size range.

Next having reference to FIG. 8, a description will be given of the electrical system preferably employed herein. While it is Vpossible that a special purpose machine could be built using only the side sealing or only the bottom sealing means disclosed herein, it is desirable in most instances that the machine be versatile so as to seal either type of wrapper fold, as provided for in the illustrated sealing channel and this electrical circuit.

The circuit shown in FIG. 8 is highly schematic and simply illustrative of the basic means which would preferably be employed. Electrical energy for this circuit is derived from power lines 230, 232 with a selector switch 234 shown in a position for sealing lapped wrapper -portions on the end faces of the article as in FIG. 1l. lt will thus be seen that the two side sealing elements 32 are connected across the power lines 230, 232 so as to be properly heated (the actual resistance elements are otherwise omitted in the drawings and conventional thermostat controls likewise omitted). Operation of the air motors 186 is controlled by solenoid valves 236 which are -of conventional design to provide for a double acting type of operation with one powered stroke of these air motors causing the side scaling elements 32 to engage the end faces of the articles as indicated in FIG. 7 and the other stroke to normally space them from the belts 194. The solenoid valves are actuated in proper timed relationship to the advance of the articles, and while the articles are at rest in the a3 position, by closing of a switch 238 which connects these solenoid valves across the lines 23), 232. The actual means employed to open and close the switch 232 may take many forms, as for example, a rotating cam connected to any element of the machine which rotates once for each cycle of operation of the wrapping machine.

When it is desired t-o seal Wrappers which have been folded as shown in FIG. 12, the switch 234 is moved to its alternate position to disconnect the previously described elements for side sealing and to connect the resistance units of the bottom sealing elements 36 across the power lines 230, 232 (again the resistance elements are shown only in FIG. 8 and conventional thermostat controls eliminated for simplicity). Operation of the air motors 224 is controlled yby solenoid valves 240 to obtain a double-acting operation, as previously indicated, through the use of conventional means. Actuation of the solenoid 240 is controlled by a switch 242 which may be opened and closed by the same or similar means as employed in closing the switch 238.

To give a further description of the operation of the present machine, it will first be assumed that the selector switch 234 is in its alternate position energizing the bottom sealing heater elements 36 and that articles with' wrappers folded in the manner of FIG. l2 are being wrapped bythe machine.

The conveyor paddle 18 advances successive articles from the position al to the position a2. The conveyor paddle 22 advances successive articles from the position a2 to a position at rest at a3 in the sealing channel 2S. The articles in the position of a3 are completely wrapped after having been discharged from the folding channel 16. Upon engagement of the paddle 22, with the article at the position a2 the clutch mechanism 64 is actuated to advance the conveyor chains 38. At this point a pair of lugs 40 is positioned immediately behind the article in the a3 position so that this article will then be advanced into the a4 position as a subsequent article is advanced into the sealing channel 28. Likewise another pair of lugs 4t) will discharge the article in the a4 position from the sealing channel as the spaced articles are advanced to the roller conveyor 42.

When the conveyor 1S completes its forward stroke and during the return stroke thereof, all of the articles remain at rest and at this time switch 242 (FIG. 8) is closed to thereby cause the air motors 224 to displace the pressure plates 21) downwardly so that the articles are forcibly engaged with the bottom sealing elements 36 to thereby effectively seal the wrapper extensions lapped beneath the article.

After the plates 210 have engaged the article for a suflicient time to obtain an effective heat seal, and in any event before subsequent advance of the conveyor chains 38, the switch 242 is opened to cause retraction of the pressure plates.

The wrapper material at this point is in a softened stage and tends to adhere to the belts 19t). Thus, as the article is advanced beyond the bottom sealing elements 36 by the conveyor lugs 40, the belts are also advanced as the article moves to the a4 position. The possibility is contemplated that a positive drive of the belts 19t) and also the belts 194 could be provided, if desirable. In any event, in the a4 position the sealed Wrapper material cools and sets before being separated from the belts 190.

At this point it will again be noted that the distance of advance of the conveyor chains 3S for each cycle of operation is substantially less than the distance of the advance of the conveyor 18 thereby minimizing the length of the belts 19t? required for both a sealing station and a cooling station.

Where the articles being wrapped have their wrappers folded as shown in FIG. ll, the selector switch 234 is in the illustrated position of FIG. 8. As each article is advanced to the a3 position, switch 238 is closed to cause the air cylinders 186 to displace the side sealing elements 32 inwardly, bringing the sealing die face f into engagement with the end faces of the article. As previously pointed out, it is preferable that the die face f be registered with the end face of the article and spaced inwardly from the four corner edges thereof so as to prevent undue pressure on these corner edges which would unduly thin the wrapper material at these points. It would be pointed out that this preferable arrangement is primarily employed for articles which are not rigid, and where the end faces of the article tend to collapse. In distinction to this, articles wrapped as shown in FIG. 12 are usually rigid, paper packages being a good example and, therefore, such registration is not required.

The side sealing elements 32 are retracted upon opening of the switch 238 prior to a subsequent advance of the conveyor chains 38 as each article is moved to the cooling station at position a3.

It will further be noted that this intermittent advance of articles through the sealing channel 38 is obtained by means which also provide for clearing articles from the folding channel after the flow of articles to the wrapping machine is halted. That is, simply by continuing the wrapping machine in operation, the conveyor chains 38 will continue in operation to completely discharge all articles onto the discharge conveyor 42.

Reference is now made to FIG. l0 for an important modification of the invention showing an alternate embodiment of the sealing channel wherein one of the side sealing elements 32' is mounted in a fixed position on the platform 150. This also results in simplification of the electrical circuit in that one of the solenoid valves 236 and the air motor previously associated with this side of the machine is eliminated. Operation of the machine is the same as before in that the remaining air motor 186 is actuated to engage the opposite end face of the article and displace the article a slight distance laterally into engagement with the face f of the fixed side sealing element 32. After pressure has been exerted for a suicient time on the end faces of the article, the remaining air motor 186 is deactuated to permit retraction of the Inovable side sealing element 32 as before and to permit advance of the article to the a4 cooling position.

It is also preferable in this modified embodiment to provide means for yieldingly spacing the belt 194 from the side sealing element 32'. Thus, a pressure bar 244 is disposed immediately beneath the die face f and arranged to engage the inner face of the belt 194. When the movable side sealing element 32' is retracted, springs 246 are effective upon mounting rods 248 to cause this bar to displace the article back to its central position and thereby space the belt 194 from the side sealing element 32'.

Having thus described the invention, what is claimed as novel and desired to be secured by Letters Patent of the United States is:

1. In a wrapping machine having a reciprocating conveyor comprising a plurality of paddles for advancing articles in spaced relation through a wrapper folding channel on the forward stroke thereof, at least one of said paddles being swingable over an article as its rests in the folding channel during the return stroke of the conveyor to a position in which the swingable paddle is spaced behind the article over which it is swung, a sealing channel aligned with said folding channel, said swingable paddle advancing successive wrapped articles to a given position within said sealing channel, said sealing channel comprising heat sealing elements and endless belts interposed between said heat sealing elements and lapped portions of the wrapper, said belts being movable along said sealing channel, means for forcibly engaging each article with said heat sealing elements while it is at rest in said given position, and a second conveyor operative during the forward stroke of said first conveyor to advance the articles through the heat sealing channel after they have been engaged with said heat sealing means.

2. In a wrapping machine having a reciprocating conveyor comprising a plurality of paddles for advancing articles in spaced relation through a wrapper folding channel on the forward stroke thereof, at least one of said paddles being swingable over an article as its rests in the folding channel during the return stroke of the conveyor to a position in which the swingable paddle is spaced behind the article over which it is swung, a sealing channel aligned with said folding Channel, said swingable paddle advancing successive wrapped articles to a given position within said sealing channel, said sealing channel comprising heat sealing elements and endless belts interposed between said heat sealing elements and lapped portions of the wrapper, said belts being movable along said sealing channel, means for forcibly engaging each article with said heat sealing elements while it is at rest in said given position, a second conveyor for intermittently advancing articles through the heat sealing channel after they have been engaged with said heat sealing means and means for so advancing the second conveyor only during the latter portion of the forward stroke of the rst conveyor, thereby minimizing the spacing between articles in said sealing channel, said belts extending beyond said heating elements a distance suflicient to remain in contact with the heat sealed portions of the wrapper after the second conveyor has been operated to advance an article from said given position.

3. A combination as in claim 2 wherein the means for so advancing the second conveyor are operatively connected to the first conveyor at substantially the time of engagement of said swingable paddle with an article in the folding channel, and further wherein the rate of advance of the second conveyor when so connected is substantially the same as the rate of advance of the first conveyor.

4. A combination as in claim 3 wherein the second conveyor comprises spaced lugs for engaging and advancing articles through the sealing channel and further wherein means are provided for operating said second conveyor in a reverse direction to maintain proper register of said lugs in the event that said first conveyor is operated in a reverse rotation prior to completing its for- Wa-rd stroke.

5. A combination as in claim 3 wherein the means for so advancing the second conveyor comprise a rack secured to said first conveyor, a pinion driven thereby, a one-Way clutch operatively connected to said pinion, the output of said one-Way clutch comprising a drive member operatively connected to said second conveyor, and means for rendering said one-way clutch operative after the first conveyor has completed the portion of its forward str-oke required for said swingable paddle to engage an article in said folding channel whereby the distance of advance of articles in said sealing channel will be substantially less than the distance of advance of the first conveyor.

6. A combination as in claim S wherein the one-way clutch is of the ratchet and single-tooth type and furthe-1' wherein means are provided for independently connecting said output member with said pinion in any position other than the start position of said output member Whereby if the first conveyor is operated in a reverse direction before completing its forward stroke the output member will also be rotated in a reverse direction to thus reverse the direction of said second conveyor and maintain the lugs thereon in proper register.

7. In a wrapping machine having a reciprocating conveyor comprising a plurality of paddles for advancing articles in spaced relation through a wrapper folding channel on the forward stroke thereof, at least one of said paddles being swingable over an article as it rests in a folding channel during the return stroke of the conveyor to a position in which the swingable paddle is spaced behind the article over which it is swung, a sealing channel aligned with said folding channel, said swingable paddle advancing successive wrapped articles to a given position within ysaid sealing channel, said sealing channels comprising a pair of heatable bottom sealing elements generally aligned with the lower surface of the folding channel at the outer sides thereof, a pair of heatable end sealing elements respectively aligned generally with the opposite sides of said folding channel, a pair of endless belts respectively trained over the upper surfaces of said bottom sealing elements, a second -pair of endless belts respectively trained over the opposed surfaces of said end sealing elements, all of said belts being freely movable along said sealing channel, means for selectively heating either the bottom or end sealing elements dependent upon the `configuration of the wrapper folds, means for forci-bly engaging the article with the heated sealing elements while it is at rest in said given position, a second conveyor for advancing articles through the heat sealing channel after they have been engaged with said heated sealing elements, means operatively connecting said second conveyor with said first conveyor at substantially the time of engagement with said swingable paddle with an article in said folding channel to advance 4said second conveyor at substantially the same rate as said first conveyor, and means normally disconnecting said second conveyor from said first conveyor during the return stroke thereof to Iprovide for intermittent advance of the second conveyor, said belts extending beyond said heat sealing elements a distance sufficient to remain in contact with the heat sealed portions of the wrapper after the second conveyor has been operated to advance an article from said given position.

8. A combination as in claim 7 wherein one of the side sealing elements is relatively fixed and means operable upon the side sealing elements ibcing heated are provided for moving the other side sealing element towards said fixed side sealing element to apply sealing heat an-d pressure to the article while it is at rest therebetween, to thereby seal folded wrapper portions on the end faces of the article, and means are provided for retracting the movable heat sealing element prior to the sealed article being advanced by the second conveyor.

9. A combination as in claim 8 wherein the side sealing elements are normally spaced from the belts trained thereover and lfurther wherein yieldable means are provided to space the belt trained over the fixed side sealing element therefrom.

10. A combination as in claim 7 wherein the side sealing elements comprise a mounting plate .and replaceable heat sealing dies secured thereto, said dies each having a configuration registered with the end faces of the article and spaced inwardly from the corner edges of said end faces.

11. A comibnation as in claim 7 wherein plunger means operable upon heating of the bottom sealing elements are provided for striking the upper Vsurface of the article to forcibly engage the article with the bottom sealing elements and seal folded wrapper portions on the undersurface of the article.

12. A wrapping machine as in claim 7 wherein at least one of the end sealing elements comprises a vertically disposed plate, means -mounting said plate -for pivotal movement about an axis parallel with and substantially aligned with the end face of an article in the sealing channel and means for swinging said plate to forcibly engage said article with said end sealing elements.

13. In a wrapping machine having a reciprocating conveyor for advancing articles on its forward stroke through a wrapper folding channel and permitting the articles to remain stationary on its reverse stroke, a sealing channel aligned with said folding channel, said reciprocating conveyor advancing successive wrapped articles to a given position within said sealing channel, said sealing channel having means for maintaining the wrapper in folded relation and comprising bottom sealing elements on opposite sides thereof, a pair of endless belts trained over said bottom sealing elements and interposed between the elements and the articles, said belts being movable along said folding channel, means operable when said article is in said given position in said sealing channel for forcibly striking the upper surface of the article and pressing it against said bottom sealing elements to heat seal folded wrapper portions on the bottom surface of the article, and means operable during the forward stroke of sai-d conveyor for advancing articles through said sealing channel.

14. In a wrapping machine having a reciprocating conveyor for advancing articles on its forward stroke through a wrapper folding channel and permitting the articles to remain stationary on its reverse stroke, a sealing channel aligned with said folding channel, said reciprocating conveyor advancing successive wrapped articles to a given position within said sealing channel, said sealing channel comprising side sealing elements respectively aligned generally with the opposite sides of said folding channel and a pair of endless belts respectively trained over the opposed faces of said sealing elements and interposed between the elements and the articles, said belts being movable along said sealing channel, belt pulleys carrying each of said belts and mounted independently of said side sealing elements, and means for ymoving at least one of said side sealing elements toward the other when an article is in said given position in said sealing channel to apply sealing heat and pressure through said belts to the article to thereby seal folded wrapper portions on the end faces of the article and means operable during the forward stroke of said conveyor for advancing articles through said sealing channel, said side sealing elements being in spaced relation from the article at the time of operation of the last named advancing means to permit advance of the articles with the belts remaining in contact with the end faces thereof.

15. A combination as in claim 14 wherein one of the side sealing elements is relatively fixed and further wherein means are provided for moving the other side sealing element toward said fixed side sealing element to apply sealing heat and pressure to the article while it is at rest therebetween.

16. A combination as in claim 15 wherein the side sealing elements are normally spaced from the 'belts trained thereover and further wherein yieldable means are provided to space the belt trained over the fixed side sealing element therefrom.

17. A combination as in claim 14 wherein means are provided for simultaneously displacing both of the side sealing elements toward each other to thus seal the folded wrapper portions on the end faces of the article.

References Cited UNTED STATES PATENTS 1,968,190 7/1934 Clark 53-33 2,745,234 5/1956 Schooler 53-379 2,801,508 8/1957 Prince 53-379 X 3,064,403 11/1962 Tokos et al 53-379 X 3,083,514 4/1963 Smith et al 53-379 X FOREIGN PATENTS 657,342 2/1963 Canada.

TRAVIS S. MCGEHEE, Primary Examiner'. 

14. IN A WRAPPING MACHINE HAVING A RECIPROCATING CONVEYOR FOR ADVANCING ARTICLES ON ITS FORWARD STROKE THROUGH A WRAPPER FOLDING CHANNEL AND PERMITTING THE ARTICLE TO REMAIN STATIONARY ON ITS REVERSE STROKE, A SEALING CHANNEL ALIGNED WITH SAID FOLDING CHANNEL, SAID RECIPROCATING CONVEYOR ADVANCING SUCCESSIVE WRAPPED ARTICLES TO A GIVEN POSITION WITHIN SAID SEALING CHANNEL, SAID SEALING CHANNEL COMPRISING SIDE SEALING ELEMENTS RESPECTIVELY ALIGNED GENERALLY WITH THE OPPOSITE SIDES OF SAID FOLDING CHANNEL AND A PAIR OF ENDLESS BELTS RESPECTIVELLY TRAINED OVER THE OPPOSED FACES OF SAID SEALING ELEMENTS AND INTERPOSED BETWEEN THE ELEMENT, AND THE ARTICLES, SAID BELTS BEING MOVABLE ALONG SAID SEALING CHANNEL, BELT PULLEYS CARRYING EACH OF SAID BELTS AND MOUNTED INDEPENDENTLY OF SAID SIDE SEALING ELEMENTS, AND MEANS FOR MOVING AT LEAST ONE OF SAID SIDE SEALING ELEMENTS TOWARD THE OTHER WHEN AN ARTICLE IS IN SAID GIVEN POSITION IN SAID SEALING CHANNEL TO APPLY SEALING HEAT AND PRESSURE THROUGH SAID BELTS TO THE ARTICLE TO THEREBY SEAL FOLDED WRAPPER PORTIONS ON THE END FACES OF THE ARTICLE AND MEANS OPERABLE DURING THE FORWARD STROKE OF SAID CONVEYOR FOR ADVANCING ARTICLES THROUGH SAID SEALING CHANNEL, SAID SIDE SEALING ELEMENTS BEING IN SPACED RELATION FROM THE ARTICLE AT THE TIME OF OPERATION OF THE LAST NAMED ADVANCING MEANS TO PERMIT ADVANCE OF THE ARTICLES WITH THE BELTS REMAINING IN CONTACT WITH THE END FACES THEREOF. 